To find out if alcohol interfered with the ability to distinguish faces where the left and right sides were uneven, he and his colleagues designed an experiment involving images of faces that were tinkered with to make them perfectly symmetrical or subtly asymmetrical. The results of the study were published by Halsey, Joerg Huber, Richard Bufton and A.C. Little in a recent issue of the journal Alcohol.

"Over an evening Joerg, Richard and I went out to the university campus bars with a laptop and asked students to participate," Halsey said.

This included students taking a quick breathalyzer test to confirm their alcohol consumption. The students were classified as either sober or intoxicated, then examined the images.

Twenty images of a pair of faces -- one symmetrical, the other asymmetrical -- and then 20 images of a single face were shown, one at a time, to 64 students. Participants were asked to state which face of each of the pairs was most attractive. They also had to determine whether each of the single faces displayed was symmetrical.

The sober students had a greater preference for symmetrical faces than did the intoxicated students. And it turned out that the sober students were better at detecting whether a face was symmetrical.

What's more, the data suggest that men were less prone to losing their symmetry-detecting ability when intoxicated than women, which was unexpected, Halsey said. The difference probably has something to do with the tendency for men to be more visually oriented and more stimulated by what they see, he said.

"Men tend to ogle more than women do," Halsey ventured.

The results add a new twist to ongoing research in this area, according to psychologist Benedict Jones of the University of Aberdeen.

"People in the past have compared attractiveness judgments of faces... to show that small amounts of alcohol see subjects give faces higher attractive ratings," said Jones.

Some researchers have suggested that this might be because people become better at detecting beauty or simply become a bit less picky.

Halsey's findings come as a surprise, said Jones, because the difference in ability between males and females was not seen in other studies where people looked at symmetry detection.

"Those studies were conducted in the lab though," said Jones. "It's possible that these new data show this sex effect because people were tested out in the community, and men and women respond in slightly different ways to that."